Prior to that it had felt hard - I thought it was hard because I wasn't an experienced salesperson.
It's got to be the same with demos - what you are demonstrating matters. If you're demonstrating something that people want, like, are interested in and understand then the demo will go one way. If you're trying to demo something they don't need/want or understand then it will go another way.
If you are demoing something people are ambivalent about for some reason then IMO you are better spending your time on making some other product rather than trying to craft the ultimate demo for the thing they are "whatever hohum" about.
It's the product/market fit thing. If you've got product market fit then the customers will pull it out of your hands.
The REALLY hard thing is of course making something people want, but I'd rather spend my time on that than being really good at selling something hohum.